Radiosignaling



Feb. 10, 1931. COHEN ET AL 1,792,144

RADIOS IGNALING Filed June 30, 1927 INVENTORS Patented FebLIO, 1931 f TERY BARK,

' 1 i Application filed June -30,

This inyention relates to the. art of radio 7 signaling. "One object ofith'ef invention is Q 7 to provide improved methods and means-for the receptionof radio signals. Another ob-j r ject. is to provide novel means of tuning.

Still anotheriobject is the'embodiment of the novel method oftuning in a tuned radioirequency amplifier for the reception off-radio.

" signals.) A further object is tosecure tuned w' radio'frequency amplification in, the recep- I 1 tion of radio signals-Without catisi'ngregenera'tion.: A

In our: o-pe'ndingiapplication, Serial No.

I scribed a new method for tuning 'radio'cir- V 'cuit'sin Which-tuningds' accomplished by the it sliding of a .metaljcylinderz over. the-iinduc-m- {tuning the system isifree fromregeneratio n;

'ZSjThi's' invention embodies the same general r principles oli tuning" butprovides modifica- "tions and improvements, whereby; greater 'efiiciencyin the operation of" the! system .is

secured; {The inyen'tion yvillbebest understood" by reference to thelaccompanying drawings,- in hich:-'

radiozfrequency amplifier," a EiguretEZ I hows a completet'radlo. receiver in" which three'iistages of tuned radio Tire-L quency amplification'isjused."

I-laying. particularii'eference to the accom- V panying' drawings in which like 'reference T 7 numerals designate corresponding 'iparts,; in

4,0 Fig.-i'1,"1jand 2 designate three electrode vvacprises inductance ieo'ils' 7, T and 8 ,Eanda fixed A ping'slof thQJ D lSf aHdHS are 1119 pos te direc- 7 also same hythes'lidin-g ofc-the-"metal tuber-191' tions-c liheutumng not the :mutual inductive relation ltisclear that a 1 current flow in the plate coil v6finduceselectro notlye forces of oppositedirectionsin' the v V ."cording'ly reater-5 until when the metalcyl c uum tubes, eachl compirising' a grid 23; plate? 1 t ger-1d filament 5". The plate l iofi tube 1 "is connectedi ;]:1r( 1igh coil 6 to: the lpositivei ter f nail fi pl e y nthe us i mn- -e Thetuning circuit of. :theseCondltubeQ100m 7 5 w ui r orW SH eo Demeter Gamamime were 9 3 ,M RYLANR; r

1 273 ser' ai tim 262,556. i

inductance the inetal cylin- V de'rs loelng insulated from the .coils thereby to preventgshort circuiting of the turns'of I thecoils when the cylinders are 'in operative position thereover efiectingtherebya change in the inductance of the coil; as Wellasa "'zchangef in the distributedcapacity between.

themetal tube 10ifand the coil=8,' and it is through 1 the variation of: these *coinbined eflectsthat: tuning is accomplished.

1 The. coils 7 and. 8 s are 'Woundonthe same I comes a single coil, but the directions of'the windings of the coils L7 'and '8 are. reversed with respect to each other. The plate coil 6 is in close mutual inductive relation to coil 7, and it is-also necessarily in mutual'indn'c tive relation to coil 8}; obviously the mutual inductance between '6 and: 8 is of opposite direction to, the" mutual in duct'ance" between the coils 61 and 7, and; is also of considerable smaller yalue; Itis: preferable tohaye' tight coupling between the miles, and 7- Which -is effected by fWinding-these two coils iniclos'e coils. T'and "8 respectively, and the 7 current; fio inthe tuned circuit 7 8'9' is'due to the difierencezin'these two induced ele ctromotiye: forces actingion the circuit; The di iference betweenitheielectrofmotiveforcein- I f ducediin-the'coil 7' and that induced ,inthe coil 8 ,'-is nothoWevenLaT-constantF'quantity,

but aries-With the iposition-fthe nietal cylinder-101cm the coili 8 thecylinder is 1 V advancedmoreandjmoreoyer the flcoil 8 the c electro-motive force induced inthe coil: 8

resultant j elec'tro-motive force becomes .ac

inder 10 complete only electrmmetiy the inter-action etwyeen' the coils F 6- and, "2'.

l/V Kha e then here; a" eoiid-ition j whereby the -fo-rce1-in-thegtunedrcin inducedgel'ectroemoti .cuit from li ate coils i6- varie f Qmthec i16 becomes lessand'lessy and th I 9D encloses the'coi'l 8 the f tieally-thag. 111 1 1 j 'c v swim erealm the ai i- 'Cuit isntu nedby the moying or the-sliding of highly important, afiording a means. for varying the effective electro-motive force induced in the tuned circuit 789 inversely in proportion to the extension of themetal tube 10 over the coil 8.

It must be noted that in rthej rnethod -of tuning used in this invention the resistance of the tuned circuit varies, increasing as the frequency increases, because of the I greater extension of themietal cylin'der over the coil in which more eddy-currents are generated, thereby increasing theeifect ve resistance of the circuit more and more as the metal ftube" 10 is advanced more and-moreover the coil 8, andto-compensate for this progressive increase 1n resistance as the metal tube 10 1s advanced 'over the coil 8,the electroi-motivc force induced in the-circuitmust be progressively increased, and this is accomplished by the expedient of reversing the windings of coils 7 and 8 as explainedabove. If not for this provisiom'then ifthe couplingbetween ;the coils 6V and Twouldbe made suffici'en'tly large to effect the proper amount ofenergy transferfwhen the metal cylinder 1O icom 1pletely encloses the coil that is,- forlthe igher frequencies, then the couplingzwould ;be;too large for the-lower frequencies when the metal cylinder 10;is partly or completely =1'ofi' the coil, the amplifier would become 'unstable and regeneration would set .in" atthose frequencies. If onitheotherhand, the cou-.

'pling between 6 and? would be just sufficient cooperate eificiently on the-lower frequencies,.it would not beright for the higher fre quencies when the metal :tube completely encloses the coil 8, in whichs'casethe resistandthislis very effectively accomplishedzby Vthe'methoddescribedabove. I

ance of the circuit is materially increased. 5 I It; is necessary therefore to; provide anarr' 4o rangement whereby the energy, transfer is progressively changed as the resistance of the c rcuitis.changedidue to the varying position of the metal cylinder: 10 on. the coil 8,

'FigureQ shows the embodiment-of the in- ;v'ention in a complete radio receiver includring three" stages of tuned radio frequency am plification; The antenna 11 ,:.is connected v through coupling condenser 12.10 the tuned circuit13 16 and groundlfi constituting the antenna. circuit. Thetuning of this i antenna circuit is efiected throughv-aryingtheinductan'celS and thedistributedcapacity. be-

tween the coil 13 andsrnetal tube l i by'the movement'of the metal tube 14' over it. The] terminals 33 and 34 connectto the grid 3-and filament 5. through aiG: battery "27 of; the

is in mutual inductiye; relation sto'ithe? coils p 21 and 22 ofthetuned circuit- 2'1-;1l22; 23fof the second tube .18. The windings-of the coilsL2l and 22 arereversed Withlreshect to each other as explainedin connection with VthedescriptionandjdiscussionofFigJIli I The of the said tuning coils of ncuits for effecting tuning.

amplifying tubes 18 and with their associated tuned circuits 212223-24 are connected in the same manner, the tWo coils of each tuned circuit are magnetically coupled differentially with the plate circuit of itspreceding tube; The terminals 25 26 of the last: tuned circuit connectto" a detector and an: audio-frequency amplifier in the usual way in thepractice of the radio art. In all thetuned circuits-tuning is effected by the movementrof "the metal cylinders 24 over their corresponding inductance coils 22. The v. condensers 80.3132 are the by-passcondensers forthe plate battery 29, filament battery"28,and C battery 27. c

rangementi'for the simultaneous tuning; of

" all of the circuits could be readilyefi'ected bymechanically connecting all the metal cylinders and operating themsimultaneously pli cation referred to above. 7 V

"We clainr: 4. g

1. In a system 'fOr radiofrequencyamplification comprising i several three electrode vacuum tubes, a tuned circu t assoclated with each ofthe vacuum tubes, means for. di-fferentially coupling magnetically-the plate of each of the :said vacuum tubes to two parts I ofthe tuning coil of the tuned circuit which a With this method of tuning'uni-controlar- V ashasbeendescribed in our cO-pendmg ,ap-

is associated with the" grid and filament I of p,

- the succeeding tube, and 'a' metallic cylinder slidable over one joffthe saidparts of ,each

2. Ina system-for radio amplification comthe said tuned cir-v prising several three electrode vacuumtube's, the grid and filament of each of the said vacuum'tubesbeing associatedwith a tuned circuitwhich consists of a fixed condenser 'and.1nductance,'-aportion of. the windings of which is wound in reversedldirection to the main winding ofthe coil,*'a metallic cylinder --slidablerover'the said. mainfwinding of the said inductance ieflecting tuning; the said,

portion of the winding as, well asthe. said ma n Winding of the tuninginductance"coil being in inductive relation tothe' 1 plate circuit of itslcorre'sp'onding prece'ding-tubefi '7 3. in {a multi-lstageitun'edradio frequency fecting igtuning," and" also eifecting; a'i'cha ig'e said portion of the winding and the said ing in 'reversedinductive relation to the plate circuitof the preceding tubegend" the effect main winding of the said inductance coil besaid plate circuit on' the said portion and, mam windings of the said inductance of the from the said plate circuit to the said tuned circuit being proportional to the difference between the mutual inductive effects of the tuned circuit.

In a multi-stage tuned radio frequency amplifier comprising several three electrode inder slidable over the said main winding thereby effecting tuning and also effecting a change in resistance of thesaid tuned circuit, the eifective resistance of thesaid tuned circuit increasing more and more as the met'a1 tube is'advanced more and more over-the said main inductance the said portiongand main;

fwindings of the saidfinductance coil being 111 reversed mutual inductive relation to the plate circuit of. the preceding tube, and'theeffect from'the said plate circuit on the said tuned circuit being proportional to the differ-- ence between the mutual'inductiveefl'ects ofv -the said plate circuit on the said portion and ,main windings' of the said inductance of the I tuned circuit f 5. In .amulti-stage tuned radio freqirencyvvacuum tubes, the-grid and filament of each amplifier comprising several three electrode of said vacuum-tubes being associated with a tuned circuit which consists of a fixed condenserand tn-inductance, a. portion ofthe Q I 1 winding ofthe said inductance being wound in a reverse direction to thatof the main winding of the saidinductancaametal cyl inder'; slidable over the said main winding thereby etfecting'tuning and also effecting achange in resistance of the saidtuned circuit, the effective. resistance of the circuit'in creasingmore andgmore as the metaltube is advanced more and more over'the 1nduc-- tance; the said windings of the said inductance coil'being in reversed mutual inductive I relationto theplate circuit of. the preceding i' 3 L tube',1and theeifect fromthe said plate cir cuit on thesaidtuned' circuitbeing propor-' I H p 'tional to the difference between the inductive I effects ofthe' said' plate circuit. on the'said .;portion and main windings of the said induc 1 g i tance of the tuned circuit'thereby compensat- "ing for the change in resistance of the'said tuned circuit, andthus efiectin'gapractically V e iiniformamplification for the. entire range of I frequencies for which'the'circuitit tunable. 'In a systemifor', the reception of radio signals comprisingan antenna circuit, a multi-stage tuned radio frequency amplifier, a

. detector and an audio-frequency amplifier,

, T {the tuned circuit of each stage comprising a;

fixed condenser, an inductancewound'in two sections, the' directions of the windings of the said twosections being reversed with respect to each other; a metal cylindershdableover each of one of thesaid'sections of each of thesaid inductances, both of the said sections of each of-the said inductancebeingin magnetic inductive relation to the plate cir cuit of its corresponding precedingtube'.

7. In a system for :thereception-of radio I signals comprising- :anantenna .circuitya multl-stage tuned radlo frequency amplifier,

a detector and an audio-frequency. amplifier, I

thetuned circuit of each stage ofthe said: multi-st'age tuned radio frequency amplifier comprising a fixed condenser and an indue tance, a portion 'ofjthe winding of the said inductance wound .in reverse direction to the 1 main windinggofthe said inductance, a metal cylinder slidable over the said main winding 1 85 thereby eflecting tuning and also-effecting a change inthe resistance of .the 'said'iuned.

tance; the said windings of the said induc tance coil being in reversed mutual inducj circuit, thejeifective resistance :of'the circuit I "increasing-more and more as the metal tube is advanced more and more overthe induce V tive relationto the plate circuit of, itsfcorres ponding preceding tube, and the effect from '7 the said platecircuit on the tuned circuit be I; a i ing proportional to the difference between the V inductive effects of the said plate circuit on the said portion and main'windingsof the said inductance of the said tuned 'circuit thereby compensating for-the; change in resistance ,of the said tuned circuit, and thus effectinga practically uniform amplification} forthe entire range of frequencies for which 7 the circuit is tuned,

: In testimony whereof we hereunto affix our slgnatures- AUeUsr r nn n,

LOUIS- COHEN; 

